DOI:10.2214/AJR.05.1580
AJR 2006; 187:S505-S507
© American Roentgen Ray Society
AJR Teaching File: Right Ventricular Mass Presenting with a Heart Murmur
Robert H. Choplin1 and
Mark W. Turrentine2
1 Department of Radiology, 0279, Indiana University School of Medicine, 550 N
University Blvd., Indianapolis, IN 46202-5253.
2 Department of Cardio-Thoracic Surgery, Indiana University School of Medicine,
Indianapolis, IN.
Received September 6, 2005;
accepted after revision January 30, 2006.
Presented at the 2005 annual meeting of the American Roentgen Ray Society,
New Orleans, LA.
Address correspondence to R. H. Choplin
(rchoplin{at}iupui.edu).
Keywords: cardiac imaging • cardiac tumor • heart murmur • MRI • thyroid gland
Case History
A 61-year-old woman has had hypertension for 5 years. At a routine
follow-up visit, a new cardiac murmur is identified. Cardiac sonography shows
a mass in the right ventricle, and the patient is sent for cardiac MRI for
further characterization.
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Fig. 1A —61-year-old woman with left ventricular mass who presents with a
heart murmur. Axial view, double inversion recovery sequence, shows mass with
relatively homogeneous intermediate signal intensity centrally and slightly
higher signal intensity peripherally that involves right ventricular free
wall.
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Radiologic Description
The images show a mass involving the right ventricular free wall just
distal to the tricuspid valve (Fig.
1A). On the double inversion recovery images, the mass has smooth
margins and relatively homogeneous intermediate signal intensity centrally and
slightly higher signal intensity peripherally (Figs.
1B,1C
and 1D). The signal intensity
is lower than that of fat but slightly higher than that of myocardium. There
is no pedunculation into the ventricular cavity. The pericardium is not
visible adjacent to the mass but can be identified adjacent to the right
ventricular wall. No pericardial effusion is seen.
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Fig. 1B —61-year-old woman with left ventricular mass who presents with a
heart murmur. Sagittal view, double inversion recovery sequence, shows mass
with relatively homogeneous, intermediate signal intensity centrally and
slightly higher signal intensity peripherally that involves right ventricular
free wall.
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Fig. 1C —61-year-old woman with left ventricular mass who presents with a
heart murmur. Horizontal long-axis view from true fast imaging with
steady-state free precession (FISP) sequence shows mass with intermediate
signal intensity involving right ventricular free wall. Mass is just distal to
but does not involve tricuspid valve annulus.
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Fig. 1D —61-year-old woman with left ventricular mass who presents with a
heart murmur. Short-axis view from true FISP sequence shows mass with
intermediate signal intensity involving right ventricular free wall.
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Differential Diagnosis
The differential diagnosis of cardiac masses includes thrombus as well as
inflammatory and neoplastic entities. Inflammatory masses include abscesses
from tuberculosis and from various bacteria, fungi, and parasites. Tumors of
the heart include myxomas, lipomas, teratomas, ectopic thyroid, metastases,
and sarcomas.
Diagnosis
The final pathologic diagnosis in this patient is ectopic thyroid tissue
involving the heart (struma cordis). No involvement of the interventricular
septum was found.
Commentary
Ectopic thyroid tissue may occur in any location along an axis from the
base of the tongue to the diaphragm. During the third embryologic week, the
thyroid begins to develop from a diverticulum of the foramen cecum in the
region of the primitive craniofacial primordium
[1]. This endodermal thyroid
primordium is tubular until the sixth embryologic week, after which it becomes
solid. At this time, under normal circumstances the distal end divides into
two lobes and becomes the primitive thyroid gland
[2]. The cephalad end is in
contact with tissue that subsequently becomes the lower face and base of the
tongue. The caudal end of the tube is in close proximity to the bulbous cordis
that subsequently develops into the heart. Failure of these tissues to
separate normally results in small islands of thyroid tissue remaining in the
developing structures. Ectopic tissue is most commonly found at the base of
the tongue followed, in descending order, by the submandibular region,
cervical lymph nodes, larynx, trachea, esophagus, mediastinum, diaphragm, and
heart [3]. Ninety-one percent
of patients with ectopic thyroid of the heart have involvement of the right
heart; only two patients have been reported with left heart involvement
[1,
4]. The mass usually involves
the interventricular septum but may extend to the free wall at or near the
base of the heart [2].
In our search of the medical literature, we found approximately 25 cases of
ectopic thyroid tissue involving the heart. Eighty percent of the patients
were women in their fourth to seventh decade. The mass may be discovered
incidentally, or patients may have symptoms of ventricular outflow tract
obstruction or arrhythmias. One patient was described with a thyroid carcinoma
in the ectopic tissue [3].
Surgical excision has been successful in patients described during the past
15-20 years.
No MRI reports of ectopic thyroid in the heart have been published, so the
MRI characteristics of ectopic thyroid are unknown. Confirmation that a
cardiac mass is the result of ectopic thyroid tissue should be sought with
either surgical removal or a thyroid-specific scintigraphy study. Once the
tissue is confirmed to be thyroid, the possibility that it is a metastasis
from a well-differentiated thyroid carcinoma should be considered. Most
metastases from these tumors involve the cervical lymph nodes and are without
other isolated organ involvement. Finally, thyroid-specific nuclear medicine
scanning should be performed postoperatively (if not done preoperatively) to
confirm that the patient has other functioning thyroid tissue
[1].
Primary cardiac tumors are unusual entities. About 70% of these are benign
and, of these, cardiac myxoma accounts for 50%. The female-to-male ratio for
occurrence of these tumors is approximately 5:4. About 5% of cases have a
familial component. Primary cardiac tumors may present at almost any age, but
they most commonly appear in the third to sixth decade of the patient's life.
An atrial myxoma is typically found on echocardiography as an echogenic mass
floating in the atrium adjacent to the atrioventricular valve. Transthoracic
echocardiography has near 100% sensitivity for detection, but transesophageal
echocardiography is better at showing the size, attachment site, and potential
obstruction at the atrioventricular valves. On MRI, these tumors have
lobulated borders with somewhat heterogeneous signal intensity that is usually
isointense to the myocardium on T1-weighted images. Myxomas usually show
enhancement with the administration of gadolinium contrast agents.
Seventy-five percent of cardiac myxomas arise in the left atrium, 10-20%
arise in the right atrium, and the remainder are equally distributed between
the left and right ventricles
[5]. Typically, these tumors
arise from the interatrial septum near the fossa ovalis. They present as a
mass that protrudes on a stalk into the cardiac chamber. When large, these
tumors may prolapse onto the atrioventricular valve orifice and result in
obstruction of blood flow. They can thus simulate mitral or tricuspid valve
stenosis.
Angiosarcoma is the most common malignant primary cardiac tumor. It
accounts for less than 2% of soft-tissue sarcomas and constitutes
approximately 8-10% of primary cardiac tumors. Approximately 300 angiosarcomas
have been reported in the world's medical literature. The male-to-female ratio
is 2-3:1. Angiosarcomas may occur at any age but are most common at 30-50
years; the first-year mortality rate is 90%. Patients may present with chest
pain, dyspnea, and malaise. At physical examination, they may have distant
heart sounds and signs of pericardial effusion
[6]. On CT, the masses are
frequently of low attenuation and have irregular, nodular borders. On MRI, the
masses have nodular irregular borders. They frequently show heterogeneous
signal intensity, with regions of high signal intensity on T1-weighted images
that are thought to result from intratumoral hemorrhage and necrosis
[7]. These masses show intense
enhancement after contrast administration on both CT and MRI. Eighty percent
of angiosarcomas arise in the right atrium and extend into the right
ventricle, with involvement of the interventricular septum, the free wall of
the right ventricle, and the right coronary artery
[6]. Functionally,
angiosarcomas result in right heart obstruction. Most angiosarcomas have
spread widely by the time of presentation
Cardiac lipoma occurs at any age and in men and women with equal frequency.
These lipomas are encapsulated tumors composed of mature fat cells. Lipomas
account for approximately 8% of primary cardiac tumors. Almost all patients
are asymptomatic, and the tumor is found incidentally. Occasional patients
have congestive heart failure or arrhythmias. Lipomas can be accurately
characterized on CT or MRI. At CT, lipomas have an attenuation of -50 H or
less. On MRI, they have high signal intensity on T1-weighted images similar to
that of fat in the mediastinum or subcutaneous tissues
[8]. The tissue signal is
decreased on fat-suppression sequences. Lipomas do not enhance with the IV
administration of gadolinium. Fifty percent of cardiac lipomas are
intracavitary and subendocardial in origin, 25% are intramyocardial, and 25%
are epicardial and extracavitary
[9]. The chambers involved, in
order of frequency, are the left ventricle, the left atrium, the right
ventricle, and the right atrium.
Objective
The educational objective of this article is to describe the imaging
features in a case of struma cordis presenting as a right ventricular
mass.
Conclusion
Cardiac struma is a rare entity of ectopic thyroid tissue presenting as a
right ventricular mass arising near the base of the interventricular septum.
Most patients are 20- to 60-year-old women, and the mass is found incidentally
or because of arrhythmia or cardiac obstruction. The treatment is surgical
excision.
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Intracardiac ectopic thyroid. Ann Thorac Surg2000; 70:1694
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- Porqueddu M, Antona C, Polvani G, et al. Ectopic thyroid tissue in
the ventricular outflow tract: embryologic implications.
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- Hirnle T, Szymczak J, Ziolkowski P, Lenartowska L. Ectopic thyroid
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Case History
Radiologic Description
